In my U.S. Pat. No. 5,133,479, issued Jul. 28, 1992, I have disclosed a flexible container (such as is commonly used for selling motor oil by the quart or liter to be poured through an automotive engine crank case filler spout or valve cover opening), the container being provided with a float valve, closable by squeezing the container body, for facilitating pouring from the container without spilling, despite the need for substantially tilting or inverting the container for pouring, before beginning the pouring.
In my U.S. Pat. No. 5,259,535, issued Nov. 9, 1993, I have disclosed an improvement or elaboration of the initial concept, and particularly details for providing the float valve arrangement as a removably installable attachment for the filler neck of a conventional screw cap closed, flexible walled oil container.
Although those inventions, and the present one, have been and are disclosed primarily in the context of an automotive engine oil container, it is believed to be clear that they have broader applicability, not only for use on or with flexible walled containers for other liquids used in a vehicular service context (such as brake fluid, automatic transmission fluid and windshield washer fluid), but in non-vehicular service contexts for controlling the pouring of other pourable liquids, such as liquid detergent, salad oil and floor wax.